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Idling rpm feedback control method for internal combustion engines

  • US 4,491,108 A
  • Filed: 04/12/1983
  • Issued: 01/01/1985
  • Est. Priority Date: 04/20/1982
  • Status: Expired due to Term
First Claim
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1. In a method for controlling the idling rpm of an internal combustion engine including an intake passage, a throttle valve arranged in said intake passage, an air passage having one end communicating with said intake passage at a location downstream of said throttle valve and another end with the atmosphere, respectively, at least one control valve arranged in said air passage for metering the quantity of supplementary air being supplied to said engine through said air passage, and at least one equipment disposed to create load acting on said engine, said method comprising controlling in a feedback manner said control valve in response to the difference between actual engine rpm and desired idling rpm during idling of said engine, detecting the total quantity of intake air inclusive of the supplementary air at each predetermined rotational angle of said engine, and varying the quantity of fuel being supplied to said engine in response to the resulting detected value of the intake air quantity, so as to maintain the air-fuel ratio of an air-fuel mixture being supplied to said engine at a desired value, the improvement comprising the further steps of:

  • (a) detecting the operative state of said equipment; and

    (b) upon detection of a transition in the operative state of said equipment, varying the supplementary air quantity through said control valve, in response to the magnitude of load on said engine, applied by said equipment, and varying the fuel quantity in a manner such that (i) when said equipment is rendered operative, the fuel quantity is increased by a first predetermined amount at each said predetermined rotational angle of said engine a first predetermined number of times, and (ii) when said equipment is rendered inoperative, the fuel quantity is decreased by a second predetermined amount at said each predetermined rotational angle of said engine a second predetermined number of times.

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